Bowling balls have to be within a standard size and weight range to comply with American Bowling Congress requirements. Only balls that comply with these requirements may be used in American Bowling Congress sanctioned play. The standard size requirements are that the balls must have a circumference between 26.704" and 27.002" and a diameter between 8.500" and 8.595". These standard balls must also not weigh more than 16 pounds, and are generally between 10-16 pounds.
Such balls are usually comprised of a spherical core formed of a homogeneous material encased by a continuous outer shell. The outer shell has a spherical exterior surface which is the rolling surface of the ball.
Each ball has two or more finger holes drilled therein. These finger holes are usually drilled into the ball after the ball has been manufactured. In custom made balls, the finger holes are positioned, and drilled at various angles, depending on the various hand size of, and finger spacing desired by, an individual bowler.
However, when these finger holes are drilled, the finger holes will tend to imbalance the ball and shift the center of gravity of the ball away from the geometric center of the ball in the direction opposite the finger holes. This imbalance will exert a force on the ball as it rolls down a bowling lane.
Bowling balls have been developed which have weight blocks imbedded in the outer edge of the core of the balls. These weight blocks are comprised of a material more dense than the remaining material of the ball. The finger holes are usually positioned adjacent the weight blocks, such that the weight blocks compensate for the loss of material when the finger holes are drilled.
The location of these weight blocks is critical since it is an American Bowling Congress requirement that the name plate or logo of a bowling ball must be placed over the heaviest portion of the undrilled ball. In addition, the center of the heaviest portion must be indicated by a mark, or a letter locator contained in the trademark, logo, etc. of the ball. In all current balls, this "heaviest portion" is determined by flotation tests, which are well known in the industry.
Moreover, it is a further American Bowling Congress requirement that each ball must pass a uniform weight test, which involves dividing the ball into six "sides" or three sets of hemispheres. The first set of sides is the top side including the finger holes and the bottom side (or hemisphere) opposite the finger holes. The second set of sides is the side left of the finger holes and the side right of the finger holes. The third set of sides is the side in front of the finger holes and the side in back of the finger holes. For balls weighing between 10-16 pounds, the weight of the top and bottom sides may only vary by three ounces, and the weight of the left and right sides, and of the front and back sides, may only vary by one ounce. Therefore, these weight blocks have to be designed and positioned to comply with these further stringent requirements.
Examples of prior bowling balls which have weight blocks are disclosed in U.S. Pat. No. 4,121,828 issued to the inventor of this invention on Oct. 24, 1978 and entitled "Bowling Ball", U.S. Pat. No. 4,183,527 issued to the inventor of this invention on Jan. 15, 1980 and entitled "Gyrostablized Bowling Ball" and U.S. Pat. No. 4,320,899 issued to Carmen M. Salvino on May 23, 1982 and entitled "Bowling Ball". However, most of the weight blocks disclosed in these patents have (1) a curved inner surface which forms an arc of a circle having a center the same as the geometric center of the ball, (2) have an inner surface which forms a tangent of a circle having the geometric center of the ball as its center and/or (3) are one piece inserts. In the balls disclosed in these prior patents, the placement of the finger holes is critical to the optimum performance of the balls. Therefore, great care must be taken in the positioning of the finger holes.
However, it is difficult to duplicate the finger holes in the same spatial relationship to the weight block(s) in the balls disclosed by these patents. Therefore, it is virtually impossible to duplicate the inertial guidance of these balls.
The bowling balls according to this invention solve this problem since the center of gravity of the balls is controlled closer (relative to the prior balls) to the geometric center of the balls. It is therefore possible to duplicate the inertial guidance of a ball in a second ball.
Therefore, there is a need in the art for a bowling ball wherein the positioning of the finger holes relative to the weight blocks may be duplicated so that the duplicate ball will have the same dynamic characteristics as the first ball. In addition, there is always a need in the bowling industry for a ball which provides extra striking power on the pins due to the internal construction of the ball. This invention addresses these needs in the art, along with other needs which will become apparent to those skilled in the art once given this disclosure.